Photographic material



United States Patent 3,311,474 PHOTOGRAPHIC MATERIAL Jozef Frans Willerns and Gerard Michiel Sevens, Wilrijk- Antwerp, and Francis Jeanne Sels, Koutich, Belgium, assignors to Gevaert Photo-Producten N.V., Mortsel- Antwerp, Belgium, a company of Belgium No Drawing. Filed Aug. 19, 1963, Ser. No. 303,124 Claims priority, application Belgium, Aug. 31, 1962, 41,926, Patent 621,948 5 Claims. (Cl. 96-29) This invention relates to the use of anti-fogging agents and stabilizers in photographic material comprising a lightsensitive silver halide emulsion layer.

It is known that such material even without being exposed becomes developable to a certain degree during storage so that during development even on the undeveloped areas a perceptible reduction of the silver halide occurs which gives rise to the so-called fog or chemical fog.

Fog depends on the development circumstances as well as on the state of the light-sensitive emulsion. Indeed, the fog increases according to the degree of development, and in constant development circumstances according to the storing time of the light-sensitive emulsion, the temperature and the relative humidity of the atmosphere wherein the emulsion is stored. For it is generally known to carry out accelerated tests on the stability of the lightsensitive emulsion by bringing it for a certain time in an atmosphere of increased temperature and/ or relative humidity. It is evident that a light-sensitive emulsion should be obtained which is as stable as possible at high temperature and high relative humidity for instance in view of its use in tropical countries. Fog arises also When some chemical substances such as hydrogen sulfide, hydrogen peroxide and strong reductors act upon the lightsensitive silver halide emulsion layer. Fog occurs generally all over the surface of the light-sensitive emulsion layer but when the emulsion is very strongly fogged the fog is mostly not uniformly spread.

Antifogging agents and stabilizers are substances which act upon the light-sensitive silver halide emulsion layer in such a way that the arising of fog on development is either prevented or strongly reduced.

It is known that certain heterocyclic compounds containing the grouping or the tautomeric form have an antifogging action when being incorporated in light-sensitive material comprising a silver halide emulsion layer. Even when being applied in little amounts said substances are very good anti-fogging agents. However, they show the disadvantage of having a more or less strong desensitizing action on the light-sensitive silver halide emulsion layer.

It has now been found that heterocyclic compounds carrying a mercapto group substituted by an alkyl carbonyl radical, an aryl carbonyl radical, an alkyl sulfonyl radical or an aryl sulfonyl radical said radicals being in their turn either or not substituted are especially good stabilizers and anti-fogging agents for a light-sensitive silver halide emulsion without causing an appreciable desensitization of the light-sensitive silver halide emulsion material.

Light-sensitive material according to the present invention comprises essentially a support and a light-sensitive silver halide emulsion layer, wherein the light-sensitive 3,31 1,474 Patented Mar. 28, 1967 emulsion layer and/or a Water-permeable layer which is in effective contact with said light-sensitive emulsion layer comprise(s) a compound of the following general formula:

H N N 1-phenyl-5-benzoylrnercapt01H-tetrazole l-phenyl-5-methylsulfonylmercaptodH-tetrazole 1-phenyl-5- (p-tolylsulfonylinercapto) -1H-tetraz0le H H 0 N 0 H3 2,2,5,5-tetramethyl-4-t p-tolylsulfonylmercapto)- A -2H-1n1idazo1ine H HaC N 2,2,5,5-tetramethyll-benzoylmercapt-A -2H-imidazoliue 1-nuph-thyl-dhenzoylmercap to-lH-tetrazole rue-@sm-s-g N Preparation of compound 1 A suspension of 1-phenyl-5-mercapto-tetrazole in benzene is refluxed. To said suspension an excess of acetyl chloride is dropwise added in 15 minutes. The suspension is completely transferred into a solution while hydrogen chloride escapes. Then the solution is refluxed for another hour on a water-bath whereupon the benzene is distilled off under vacuum. An oil is obtained which is transformed into a solid white product having a melting point of 62-64 C. by crystallization from carbon tetrachloride.

Preparation of compound 2 To a suspension of 1-phenyl-S-mercapto-tetrazole in water an equimolar amount of sodium hydroxide is added whereupon the mixture is cooled till 0 C. and an equimolar amount of benzoyl chloride is added. After strongly shaking at room temperature a White solid product is obtained which is sucked ofi washed with diluted sodium hydroxide and with water.

After drying, the product is recrystallized from alcohol or from carbon tetrachloride. Melting point: 80 C.

Preparation of compound 3 To a solution of 1-phenyl-5-mercapto-tetrazole in ether an equimolar amount of pyridine is added. The mixture is cooled till 15 C. whereupon an equimolar amount of methyl sulfochloride is dropwise added. Then the mixture is stirred for 2 hours at 15 C. and stored for 24 h. at about 0 C. The crystals formed are sucked off, washed with water, dried and recrystallized from chloroform. Melting point: 130 C.

Preparation of compound 4 To a solution of 1-phenyl=5-mercapto-tetrazole in ether an equimolar amount of pyridine is added. The mixture is cooled till 10 C. and an equimolar amount of toluene sulfochloride is added. Then the solution 'formed is allowed to stand at room temperature for some days. The crystallized product is sucked ofi, knead with water and after drying recrystallized from benzene. Melting point: 142 C.

Preparation of compound 5 To a solution of 2,2,5,5-tetrarnethyl-4-imidazolidinethione in ether an equimolar amount of pyridine is added. The mixture is cooled till 15 C. and an equimolar amount of toluene sulfochloride is added. The solution is allowed to stand for 24 hours whereupon the crystals formed are sucked off nad recrystallized from methyl glycol. Melting point: 240 C.

Preparation of compound 6 To a suspension of 2,2,5,5-tetramethyll-imidazolidinethione in water an equimolar amount of sodium hydroxide is added whereupon the mixture is cooled till 0 C. and an equimolar amount of benzoyl chloride is added. After shaking for some days a yellow oil is obtained which solidifies after some days. The product is recrystallized from toluene. Melting point: 260 C.

Preparation of compound 7 To a suspension of 5-(4-pyridyl)-2-mercapto-1,3,4-oxadiazole in a mixture of water and acetone an equimolar amount of sodium hydroxide is added. Then an equimolar amount of toluene sulfochloride dissolved in acetone is added and the mixture is stirred for some hours. The precipitate formed is sucked oif and redissolved in chloroform. Finally the chloroform solution is evaporated and the solid product obtained is recrystallized from ethanol. Melting point: 140 C.

Preparation of compound 8 To a suspension of 0.05 mole of: l-naphthyl-S-mercaptotetrazole in water is added 0.05 mole of sodium hydroxide dissolved in water. To the solution obtained 0.05 mole of benzoyl chloride is added while cooling. Then the mixture is shaken for 8 hours while cooling. The aqueous mass is extracted with ether, whereupon the ether solution is washed with 1N sodium hydroxide and with water. Finally the ether solution is dried and the ether is distilled off. The product obtained is recrystallized from alcohol. Melting point: C. 7

Preparation 0 compound 9 In a three-necked flask fitted with a stirrer, a cooler and a dropping funnel are placed a solution of 0.05 mole of 1-naphthyl-S-mercapto-tetrazole in 450 cm. of ether and 0.05 mole of pyridine. The solution is cooled with ice-water and then 0.05 mole of p toluene sulfochloride in cm. of ether is added dropwise in 45 minutes. After strongly cooling for some hours the product having a melting point of C. is obtained. After recrystallization from alcohol the melting point is 122 C.

These compounds bearing a substituted mercapto group may also be incorporated in a light-sensitive material of use in the silver salt diffusion transfer process. In that case they do not act merely as a stabilizer but also as a black-toning agent. In the last case they may also be incorporated in the image-receiving material If these compounds are to be incorporated into the light-sensitive silver halide emulsion layer this may be effected by adding them to the emulsion in whatever stage of its preparation.

Instead of incorporating the compounds in the silver halide emulsion layer they may also the incorporated into a Water-permeable layer present at the same side of the support as the light-sensitive silver halide emulsion layer for instance into a gelatin covering layer, into an intermediate layer, etc.

The adding of said compounds bearing a substituted mercapto group mostly occurs from a solution of said com-pounds for instance in water, a lower aliphatic alcohol and acetone.

The emulsions used may be sensitized according to a known method. They may be chemically sensitized by ripening in the presence of small amounts of sulfur containing compounds such as allyl isothiocyanate, allyl thiourea, sodium thiosulfate etc. The emulsions may also be sensitized by means of reductors for instance tin compounds as described in the French patent specification 1,146,955 and in the Belgian patent specification 568,687, imino-a-mino methane sulfinic acid compounds as described in the British patent specification 789,823 and small amounts of noble metal compounds such as gold, platinum, palladium, iridium, ruthenium and rhodium. Further it is possible to sensitize the emulsions by means of polyalkylene oxide derivatives for instance polyethylene oxide having a molecular weight comprised between 1000 and 20,000, further condensation products of alkylene oxides with aliphatic alcohols or glycols, cyclic dehydration products of hexitoles, alkyl substituted phenols, aliphatic carboxylic acids, aliphatic amines and diamines or with aliphatic atmides. Said condensation products have a molecular weight of at least 700 and preferably above 1000.

For obtaining defined effects said sensitizers may of course be applied together as described in the Belgian patent specification 537,278 and the British patent specification 727,982.

Further the said compounds with substituted mercapto group may be applied to optically as well as to nonoptically sensitized emulsions.

It is also possible for obtaining defined effects to use these compounds in combination with other known The following examples illustrate the present invention.

Example 1 To a series of the same high-sensitive gelatin silver bromo-iodide emulsions (about 3.5% of iodide) are added 0.055 millimole of stabilizers according to the present invention and other comparative stabilizers per kg. of emulsion. After the classic chemical ripening said emulsions are coated onto a support and dried. The materials thus obtained are cut into two strips A and B. The strips A are immediately exposed for 4 seconds and developed for 4 minutes in the developing bath of the comp ositioin given below whereas the strips B first are stored for 5 days at high temperature and high relative humidity before being treated likewise.

The developing bath has the following composition:

\ G. N-methyl-p-aminophenol hemisulfate 1.5 Hydroquinone 6 Sodium sulfite 100 Sodium carbonate 80 Potassium bromide 2 Trisodium salt of ethylene diamine tetra-acetic acid 1.5

Water, up to 1000 cm. 3.

After the treatment in the stop-bath, Washing and fixing the following results are obtained:

Change in Change in gradation sensitivity relative to relative to the blank the blank Stabilizer applied Fog value of Fog value of material material strips A strips B after an after an incubation incubation period of period of 5 days, 5 days, percent percent None 0.11 0.35 Phenylmercaptotetrazole- 0. 04 0. 10 20 26 Compound 1 0.05 0.10 -8 5 Compound 2.- 0. 03 0. 08 9 1 Compound 3 O. 03 0.10 7 5 Compound 4.-.. 0. 04 0.11 8 2 2,2,5,fi-tetramethyli-imidazolinethione 0.07 0.11 18 -32 Compound 6. 0. 07' 0.07 2 +1 5-(pyridyl-2-mereapto-l,3,4)-

oxadiazole 0. 06 0. 13 16 42 Compound 7 0. 06 0. 11 2 8 stabilizers such as 7-hydroxy-5-alkyl-s-tr1azolo-(2,3-a) Example 2 pyrimidines for instance in high-sensitive emulsions comprising a development accelerator of the polyoxyalkylene type.

The compounds according to the present invention may be applied in all kinds of emulsions such as silver bromo-iodide emulsions, silver bromide emulsions, silver bromo-chloride emulsions, silver chloride emulsions and silver chloro-iodide emulsions thus in all usable negative and positive photographic film and paper kinds.

The amount of compounds with substituted mercapto group may vary according to the use thereof as stabilizer and/or as black-toning agent, the kind of silver halide or mixture of silver halides applied, the ripening state, the occasional presence of other emulsion additives such as color couplers, optical bleaching agents, anti-oxidation agents, black-toning agent etc.

The amount of stabilizer generally varies from 0.01 to to 3 g. per mole of silver halide. In special circumstances, however, for instance for obtaining defined effects, larger amounts may be applied.

The compounds bearing a substituted mercapto group act as black-toning agent in a diffusion transfer process and further have a specially strong anti-fogging and stabilizing action on a light-sensitive silver halide emulsion layer without, however, having an appreciable desensitizing action.

1 kg. of green-sensitized gelatino silver chloro-iodide emulsion (0.6% of iodide) prepared starting from 45 g. of silver nitrate and comprising 250 mg. of compound 1 is coated onto a paper support in such a way that it covers 25 sq.m. of support.

The light-sensitive material thus obtained is image-wise exposed and then passed together with an image-receiving material through an ordinary treating bath for producing diffusion transfer images. After a contact period of 20 seconds both materials are separated and a neutr black positive image of the original is obtained.

A same result is obtained when incorporating into the emulsion 250 mg. of compound 3 instead of 250 mg. of compound 1. With a blank material containing no compound acording to the present invention a yellowishbrown diffusion transfer image is obtained.

When repeating the same test using a material containing instead of compounds '1 and 3 a same amount of the compound bearing a free mercapto group the light-sensitive material thus prepared shows, immediately after adding said compound a decrease in sensitivity and gradation contrary to the material comprising the compound with substituted mercapto group.

We claim:

1. Photographic material comprising at least one lightsensitive silver halide emulsion layer wherein said matewherein:

Z represents the atoms necessary to complete a heterocyclic ring, and

A represents a member selected from the group consisting of a -COR group and a SO R group wherein R represents a member selected from the group consisting of an alkyl radical, and an aryl radical.

2. Photographic material according to claim 1, wherein said compound is incorporated in the light-sensitive emulsion layer.

3. Image-receiving material for use in a silver complex diffusion transfer process comprising in at least one water-permeable layer a compound of the following formula:

C-S-A 8: group consisting of an alkyl radical, and an aryl radical.

4. Imagereceiving material according to claim 3, wherein said compound is incorporated in the image-receiving layer.

5. A photographic silver complex diffusion transfer process according to which a positive image of an original is obtained by development of an image-wise exposed light-sensitive silver halide emulsion layer and diffusion of the non-developed complexed silver halide from the emulsion layer to an image-receiving material Where the complexed silver halide is transformed into a silver containing image in the presence of development nuclei and at least one compound of the following formula:

wherein:

Z represents the atoms necessary to complete a heterocyclic ring, and

A represents a member selected from the group consisting of a COR group and a -SO R group wherein R represents a member selected from the group consisting of an alkyl radical, and an aryl radical.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

CAROLYN E. DAVIS, Assistant Examiner. 

1. PHOTOGRAPHIC MATERIAL COMPRISING AT LEAST ONE LIGHTSENSITIVE SILVER HALIDE EMULSION LAYER WHEREIN SAID MATERIAL COMPRISES IN AT LEAST ONE WATER-PERMEABLE LAYER A COMPOUND OF THE FOLLOWING FORMULA: Z<(-C(-S-A)=N-) WHEREIN: Z REPRESENTS THE ATOMS NECESSARY TO COMPLETE A HETEROCYCLIC RING, AND A REPRESENTS A MEMBER SELECTED FROM THE GROUP CONSISTING OF A -COR GROUP AND A -SO2R GROUP WHEREIN R REPRESENTS A MEMBER SELECTED FROM THE GROUP CONSISTING OF AN ALKYL RADICAL, AND AN ARYL RADICAL. 